Recently, in a commutator motor with a brush used for a vehicle, while reduction in weight, reduction in thickness, improvement in efficiency, increase in life, improvement in reliability, and reduction in cost have been progressing, similar requirements for motors from a low-output motor to a high-output motor are made. In a conventional technology, as specifications to cover surrounding of a commutator motor with a brush, a method for inserting a brush assembly into an insulating resin bracket provided with a brush sliding groove (for example, refer to PTL 1), or a motor in which metal cover plate 47 is pressed into an insulating resin brush holder, or a motor using a metal box integral type is known.
In the conventional technology, specifications in which metal cover plate 47 is pressed into the insulating resin brush holder has a problem in a heat-resisting property of the insulating resin brush holder. That is, there is a problem, that a resin wall of the brush holder exceeds a heat resistant temperature of the resin due to heat generated by a brush of a high-output motor, and the brush and the resin wall of the brush holder are fixed to each other to reach non conduction, for example.
Additionally, in the method using the metal box integral type, the metal box is directly mounted on a flat brush holder in order to fix the metal box, and therefore a part, to which the insulating resin brush holder is fixed, needs to be located at a high position.